Intraocular lenses have for many years had a design of a single optic with loops attached to the optic to center the lens and fixate it in the empty capsular bag of the human eye. In the mid '80s silicone plate lenses were introduced, which were 10.5 mm in length and had a 6 mm optic. These lenses did not fixate well in the capsular bag, but resided in pockets between the fused anterior and posterior capsules. The first foldable lenses were all made of silicone.
In the mid 1990s an acrylic material was introduced as the optic of lenses. The acrylic lens had a biconvex optic with a straight edge into which was inserted loops to center the lens in the eye and fixate it within the capsular bag. Claims were made that the material of this lens significantly reduced posterior capsular opacification. It later became apparent that the property of the lens that reduced posterior capsular opacification was not necessarily related to the material, but to the relatively sharp or “square edge” on the posterior surface of the optic. The optic, when it is sealed within the capsular bag, presented a square sharp edge to the posterior capsule, which is tightly pulled against it during the period of fibrosis, preventing the ectodermal cells from growing across the posterior capsule behind the optic. A barrier was formed which successfully reduced the posterior capsular opacification rate. Silicone optic lenses were manufactured with a similar so-called straight edge in the posterior surface of the optic. Studies were done and the instance of posterior capsular opacification was found to be the same in the silicone lenses as in the acrylic lenses; therefore the material was not the cause of the reduction of the reduction in posterior capsular opacification. The sharp edge of the optic where the posterior optic surface joined the edge of the lens was the prime reason for the reduced incidence of posterior capsule opacification.
Recently accommodating intraocular lenses have been introduced to the market, which are modified plate haptic lenses and, like the standard silicone plate haptic lenses, have no clear demarcation between the junction of the plate with the optic's posterior surface. A plate haptic lens may be defined as an intraocular lens having two or more plate haptics where combined junctions with the optic represent one quarter or more of the circumference of the optic.